Baffle assembly and heat exchanger with expanding baffles

ABSTRACT

An improved baffle assembly for heat exchanger tubes comprising a shaft and at least one opposing pair of expanding baffles positioned coaxially on the shaft, each expanding baffle comprising a central hub portion and a plurality of extension portions each radiating outward from the hub portion at complementary oblique angles so that the central hub portions of each baffle are spaced apart along the shaft and the distal ends of the extension portions of each baffle are brought into physical contact.

FIELD OF THE INVENTION

An improved baffle assembly and heat exchanger with expanding bafflesused in cooking equipment. Specifically, the improved baffle assemblyand heat exchanger includes expanding baffles which can be installed innew gas powered fryers or retrofitted within heat exchangers of old gasfryers to increase the efficiency of heat transfer via gas flowdisruption and heat conduction.

BACKGROUND

Deep-fat fryers are common cooking appliances used in restaurants,institutional kitchens, and fast-food establishments for cooking avariety of food products, such as French fries, fish, chicken, and thelike. The food product is cooked by totally immersing it within a vat ortank that is filled with oil or shortening heated up to about 350° F.The oil may be heated using a heat exchanger, which may take the form ofone or more heat exchange tubes that run through the cooking vat belowthe surface of the oil through which heated gas is forced or drawn. Agas burner may be provided at one end of the heat exchanger tube to heatthe gas circulating therethrough so that the heat is transferred to thecooking oil. A flue may be provided on the opposite end of the heatexchanger tube to permit the controlled discharge of combustionby-products. In operation, heated gas travels through the heat exchangertube which heats its inner walls via convection. In some fryers, theheat exchanger tube that runs through the cooking vat contains one ormore bends or turns to lengthen the portion of the heat exchanger tubein contact with the oil thereby increasing the surface area availablefor heat transfer to the oil.

In the operation of fryers, maintaining a consistent oil temperature ispreferred. The placement of food items in the oil bath, particularlyfrozen food items, reduces the temperature of the oil. Food cooked attemperatures below the optimum temperature will retain oil, becomesoggy, and generally not exhibit the desired crispness. Thus, it ispreferable to have a quick recovery in oil temperature after food isplaced in the oil. While a quick recovery time may be achieved withpowerful burners, doing so with greater efficiency is more challenging.

It is known in art to increase heat transfer efficiency in fryers byincorporating baffles and other structural elements within the flowpassages of heat exchanger tubes to impart turbulence and retard theflow of heated gas through the system in order to increase theefficiency of heat transfer. Energy-efficient fryers employing suchconventional baffles, however, are more complicated to manufacture andare usually more expensive than simpler, less efficient fryers.Moreover, the baffles they employ are not readily adaptable to existing,low-efficiency fryers.

There remains a need to improve heat transfer efficiency in new fryersand to easily and affordably retrofit old fryers. While nominalimprovements have been made in the past, the present inventionrepresents a significant improvement in efficiency of both new andexisting fryers, in terms of energy, ease, adjustability, and cost ofoperation.

SUMMARY OF THE INVENTION

According to one aspect of the invention, there is provided an improvedbaffle assembly comprising a shaft and at least one opposing pair ofexpanding baffles positioned coaxially on the shaft, each expandingbaffle comprising a central hub portion and a plurality of extensionportions each radiating outward from the hub portion at complementaryoblique angles so that the central hub portions of each baffle arespaced apart along the shaft and the distal ends of the extensionportions of each baffle are brought into physical contact. The distalends of the extension portions may be provided with complementaryengagement members, such as teeth, grooves, pins, or the like, tostabilize the engagement of the distal ends of complementary extensionportions. One or more spacers may be positioned on the shaft in orderprevent the at least one pair of expanding baffles from sliding alongthe axis of the shaft when assembled. Spacers may also be positionedalong the shaft between opposing pairs of expanding baffles.

The shaft may be provided with a threaded end capable of accommodating anut for maintaining the pairs of baffles on the shaft and forcompressing the pairs of baffles together. The baffle assembly may beinstalled as part of a newly constructed fryer, heat exchanger, andother similar system, or as a simple, affordable, after-market bafflesystem to increase the energy efficiency of existing fryers, heatexchangers, and other similar systems through retrofitting andmodification.

According to another aspect of the invention, there is provided animproved heat exchanger comprising at least one heat exchanger tube forthe passage of a heated gas and a baffle assembly positioned within theat least one heat exchanger tube wherein the baffle assembly comprises ashaft having a threaded end and at least one opposing pair of expandingbaffles positioned coaxially on the shaft, each expanding bafflecomprising a central hub portion and a plurality of extension portionseach radiating outward from the hub portion at complementary obliqueangles so that the central hub portions of each baffle are spaced apartalong the shaft and the distal ends of the extension portions of eachbaffle are brought into physical contact. In another embodiment, theheat exchanger comprises at least one heat exchanger tube for thepassage of a heated gas and a plurality of baffle assemblies positionedwithin the at least one heat exchanger tube. In yet another embodiment,the heat exchanger comprises a plurality of heat exchanger tubes for thepassage of a heated gas and a plurality of baffle assemblies positionedwithin each heat exchanger tube.

Engagement of the threaded end of the shaft of the baffle assembly witheither a nut or a tapped hole within heat the exchanger tube causes theat least one pair of expanding baffles to compress against each other sothat the central hub portions of each pair of baffles move closertogether and the extension portions of each pair of baffles flatten andexpand outward to bear against the inner wall of the heat exchangertube. So configured, the baffle assembly forms a series of fixedpassageways that act to increase flow turbulence of heated gas while thebaffles themselves provide multiple points of direct contact with theheat exchanger tube to promote heat transfer from the baffles to theinner wall of the heat exchanger tube via conduction and increase theefficiency of the entire system.

BRIEF DESCRIPTION OF THE FIGURES

Objectives and advantages disclosed herein will be understood by readingthe following detailed description in conjunction with the drawings, inwhich:

FIG. 1 shows an exploded view of an exemplary baffle assembly;

FIG. 2 shows an overhead view of a heat exchanger within a fryer inwhich baffle assemblies are positioned in series within the heatexchanger tubes.

DETAILED DESCRIPTION

In the description herein, numerous specific details are provided, suchas examples of components and/or methods, to provide a thoroughunderstanding of embodiments of the present invention. One skilled inthe relevant art will recognize, however, that an embodiment of theinvention may be practiced without one or more of the specific details,or with other apparatus, systems, assemblies, methods, components,materials, parts, and/or the like. In other instances, well-knownstructures, materials, or operations are not specifically shown ordescribed in detail to avoid obscuring aspects of embodiments of thepresent invention.

Reference throughout this specification to “one embodiment,” “anembodiment,” or “a specific embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention and notnecessarily in all embodiments. Thus, respective appearances of thephrases “in one embodiment”, “in an embodiment”, or “in a specificembodiment” in various places throughout this specification are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics of any specificembodiment of the present invention may be combined in any suitablemanner with one or more other embodiments. It is to be understood thatother variations and modifications of the embodiments of the presentinvention described and illustrated herein are possible in light of theteachings herein and are to be considered as part of the spirit andscope of the present invention.

Furthermore, the term “or” as used herein is generally intended to mean“and/or” unless otherwise indicated. Combinations of components or stepswill also be considered as being noted, where terminology is foreseen asrendering the ability to separate or combine is unclear. As used in thedescription herein and throughout the claims that follow, “a,” “an,” and“the” includes plural references unless the context clearly dictatesotherwise. Also, as used in the description herein and throughout theclaims that follow, the meaning of “in” includes “in” and “on” unlessthe context clearly dictates otherwise.

It is intended that the invention not be limited to the particular termsused in the appended claims and/or to the particular embodimentdisclosed as the best mode contemplated for carrying out this invention,but that the invention will include any and all embodiments andequivalents falling within the scope of the appended claims. Thus, thescope of the invention should not be limited to specific embodimentsshown and described, but should also include all changes andmodifications which come within the scope of the appended claims.

Referring to the embodiment shown in FIG. 1, one aspect of the presentinvention is a baffle assembly 10 comprising a shaft 12 having athreaded portion 14, two pairs of expanding baffles 20, 30, 40, and 50mounted coaxially on the shaft 12, a spacer 60 mounted coaxially on theshaft 12 between each pair of expanding baffles, and a nut 70 mounted onthe threaded portion 14 of the shaft 12. In another embodiment, thebaffle assembly may comprise only one pair of expanding baffles. In ayet another embodiment, the baffle assembly may comprise three or morepairs of baffles.

Each expanding baffle 20, 30, 40, and 50 comprises a central hub portion22, 32, 42, and 52, and extension portions 24, 34, 44, and 54, whereineach extension portion radiates outward from the hub portion to which itis attached. When baffles are arranged in opposing pairs, the extensionportions 24, 34, 44, and 54 of each baffle 20, 30, 40, and 50 extendoutward at complementary oblique angles so that the central hub portions22, 32, 42, and 52 of each baffle pair are spaced apart along the shaft12 and the distal ends of the extension portions 24, 34, 44, and 54 ofeach baffle pair are brought into physical contact. As shown in FIG. 1,the distal ends of the extension portions 24, 34, 44, and 54 may beprovided with interlocking engagement members, such as teeth, grooves,pins, or the like, to stabilize the engagement of the distal ends ofcomplementary extension portions of each baffle pair. In anotherembodiment, the distal ends of the extension portions 24, 34, 44, and 54may be provided with complementary profiles to permit stable engagementwithout the use of interlocking engagement members.

While shaft 12 as shown in FIG. 1 is a hex bolt having a head 13 and athreaded portion 14, shaft 12 may be any suitably rigid, elongatedstructure capable of accommodating at least one pair of expandingbaffles and a mechanism for compressing the pairs of baffles together.Suitable mechanisms for compressing baffle pairs include, but are notlimited to, a nut, a ratchet, a pawl, or other similar mechanism capableof applying an axially compressive force on pairs of baffles. The baffleassembly of the present invention may be used, singly or in combination,in one or more heat exchanger tubes to impart greater turbulence to theflow of heated gas and to provide multiple points of physical contactwith the inside surface of the heat exchanger tubes for heat conduction,increasing efficiency of the entire system.

Referring to the embodiment shown in FIG. 2, another aspect of thepresent invention is a heat exchanger 100, comprising first and secondheat exchanger tubes 110 and 120 for the passage of a heated gas throughfryer 130, a first series of baffle assemblies 140, 150, and 160positioned within the first heat exchanger tube 110, and a second seriesof baffle assemblies 170, 180, and 190 positioned within the second heatexchanger tube 120. While the heat exchanger shown in FIG. 2 comprisestwo heat exchanger tubes, heat exchangers within the scope of thepresent invention may comprise a single heat exchanger tube or aplurality of heat exchanger tubes. Further, while the heat exchangertubes shown in FIG. 2 are each provided with a single, 180 degree turn,heat exchanger tubes within the scope of the present invention maycomprise a straight tube (i.e., having no turns) or tube having aplurality of turns. As the number of turns increases the path traveledby heated gases lengthens as well as the residence time of heated gaseswithin the fryer.

The baffle assembly of FIG. 1 may be installed in heat exchanger tubes,either singly or in series. As shown in FIG. 2, baffle assemblies 140,150, and 160 are provided in series in heat exchanger tube 110, andsimilarly, baffle assemblies 170, 180, and 190 are provided in series inheat exchanger tube 120 wherein each baffle assembly comprises a shafthaving a threaded end and two opposing pairs of expanding bafflespositioned coaxially on their respective shaft, each expanding bafflecomprising a central hub portion and a plurality of extension portions,each radiating outward from their respective hub portion atcomplementary oblique angles so that the central hub portions of eachbaffle are spaced apart along the shaft and the distal ends of theextension portions of each baffle are brought into physical contact.Each series of baffle assemblies may also comprise one or more spacersbetween pairs of expanding baffles and/or between baffle assembliesthemselves.

For the style of fryer 130 shown in FIG. 2, one method for installingexpanding heat baffles in a heat exchanger involves removing the exhaustpipes 200 and 210 (and/or any other items blocking access to an open endof heat exchanger tubes 110 and 120), inserting the baffle assembliesinto heat exchanger tube 110 and 120. Referring to FIG. 1, each baffleassembly is secured within the heat exchanger tube by advancing nut 70along threaded portion 14 of shaft 12 such that the hub portions of eachpair of expanding baffles compress against each other, deforming theextension portions such that they flatten out and increase in diameter.By flattening out and increasing the diameter of the extension portionsof the expanding baffles within the heat exchanger tube, the distal endsof the extension portions bear against the inner wall of the heatexchanger tube and secure the baffle assembly within the heat exchangertube.

Once installed, exhaust pipes 200 and 210 (and/or any other itemspreviously removed) are replaced, and the system is charged with gas,and ignited. Once heated gas flows through burners 220 and 230 and heatexchanger tubes 110 and 120, it will be slowed and disrupted by thebaffle assemblies 140, 150, 160, 170, 180, and 190, which willthemselves be heated, providing more efficient heat transfer to the oilbath on the fryer 130.

The foregoing heat transfer improvement can be easily adapted to othercooking equipment such as, for example, pasta cookers andrethermalizers.

What is claimed is:
 1. A baffle assembly comprising: a shaft; and atleast one opposing pair of expanding baffles positioned coaxially on theshaft, wherein each baffle has a central hub portion and a plurality ofextension portions, each extension portion radiating outward to a distalend from its respective hub portion at complementary oblique angles sothat the central hub portions of each baffle are spaced apart along theshaft and the distal ends of the extension portions of each baffle arebrought into physical contact.
 2. The baffle assembly of claim 1,comprising at least two opposing pairs of expanding baffles positionedcoaxially on the shaft, wherein each baffle has a central hub portionand a plurality of extension portions, each extension portion radiatingoutward from its respective hub portion at complementary oblique anglesso that the central hub portions of each baffle pair are spaced apartalong the shaft and the distal ends of the extension portions of eachbaffle pair are brought into physical contact.
 3. The baffle assembly ofclaim 2 further comprising a spacer positioned along the shaft betweenthe at least two opposing pairs of expanding baffles.
 4. The baffleassembly of claim 1, wherein the shaft is provided with a threaded end.5. The baffle assembly of claim 4, further comprising a nut positionedon the threaded end of the shaft.
 6. The baffle assembly of claim 1,wherein the distal ends of the extension portions of each expandingbaffle is provided with complementary profiles for stable engagement. 7.A heat exchanger, comprising: a heat exchange tube, and at least onebaffle assembly positioned within the heat exchange tube, wherein the atleast one baffle assembly comprises a shaft and at least one opposingpair of expanding baffles positioned coaxially on the shaft, whereineach expanding baffle has a central hub portion and a plurality ofextension portions, each extension portion radiating outward from itsrespective hub portion at complementary oblique angles so that thecentral hub portions of each baffle are spaced apart along the shaft andthe distal ends of the extension portions of each baffle are broughtinto physical contact.
 8. The heat exchanger of claim 7, comprising aplurality of said baffle assemblies positioned in series within the heatexchange tube.
 9. The heat exchanger of claim 7, comprising a pluralityof heat exchange tubes.
 10. The heat exchanger of claim 9, wherein eachheat exchange tube is provided with at least one said baffle assembly.11. The heat exchanger of claim 9, wherein a plurality of said baffleassemblies are positioned in series within each heat exchange tube.